Bubbling Slime Recipe for Sensory Tubs

These bubbling slime sensory tubs are my son’s new favorite thing! Which is pretty impressive, because in the past he’s always refused my invitations to play with the various gooey slime recipes I’ve experimented with in our kitchen. But between the exciting bubbling action that lasts for hours and hours — ours was still bubbling the next day! — and all of the pretend play possibilities, he’s been willing to get his hands messy to play. He’s also enjoyed making this no-cook slime recipe with me, and keeps brainstorming more Star Wars sensory tubs for us to make in the future.

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This slime recipe is made entirely with edible ingredients, and the key to it is xanthan gum, a common ingredient in gluten-free baking. It’s an ingredient I’ve been intrigued with ever since I made vegetarian marshmallows for my food blog. (That was a science experiment all on its own!)

I’ve been playing with xanthan gum slimes on and off for the past several months, but never blogged about them because a) I was the only one playing with them in our house and b) it was a bit difficult to work slime into the prevailing theme over at Play Trains! Wooden trains and slimes don’t exactly mix, you know.

The bubbling action is caused by a thin layer of baking soda at the bottom of the sensory tub. With the slime at just the right consistency, it slows down the reaction between the vinegar in the slime and the baking soda at the bottom of the tub. For us, they kept reacting for at least 24 hours! My son was super impressed by that one, and it was a great way to observe baking soda and vinegar reaction over a long period of time.

Of course, you can stir the slime and the baking soda up and speed up the reaction, like we did above. (Make sure you’re prepared for overflow!) But even then it lasts much, much longer than plain baking soda and vinegar, and the slimy foam holds the bubbles for a long time.

And this is what Yoda’s swamp looked like when it was finally finished actively bubbling. All those trapped bubbles! Isn’t it gorgeous?

We made another batch of the slime earlier today, this time tinted blue, and put it in a squirt bottle. We set up a container with some Angry Birds figures sitting on baking soda, and he had a great time squirting the birds and pigs “at the pool”. We’re looking forward to finding more fun ways to play with this slime!

Safety Note: While all of the ingredients are edible, and this should be safe enough if a child tastes it once or twice, xanthan gum is a substance that thickens water. To be on the safe side, I wouldn’t let a child eat the slime, and I would supervise any activity where this slime is used.

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